I put a radio in my 1100RT for a while, a few things come to mind. Using the official radio mounting cage made fitting the radio nice and easy, fitting a really good aerial was difficult as was arranging a satisfactory remote control that was waterproof. If I was doing this again I’d probably get the BMW factory kit S/H and try and marry that up to a Bluetooth stereo transmitter, it may cost more, but its surely going to be easier